This invention relates to a method of processing low concentration aqueous solution of agent for processing synthetic fibers containing potassium alkyl phosphate which is solid at room temperature and being stable over a long period of time such that the agent can be attached to synthetic fibers as desired for a long time.
At spinning and fabrication factories of synthetic fibers, agents for processing synthetic fibers containing potassium alkyl phosphate, and normally potassium alkyl phosphate having alkyl group with 12-22 carbons atoms, are frequently applied to synthetic fibers. Generally, such an agent is produced as a high concentration aqueous solution or a paste with concentration of about 20-60 weight % at a chemical factory different and apart from the production or fabrication factories of synthetic fibers, and a low concentration aqueous solution of about 0.1-10 weight % is prepared after it is transported to a spinning or fabrication factory to be applied to synthetic fibers, as disclosed, for example, in Japanese Patent Publication Tokkai 2002-20971.
It is usually several months to a half year from when such a high concentration aqueous solution or a paste of agent for processing synthetic fibers is produced until it comes to be actually used after being stored and transported. Since 40-80 weight % of such a high concentration aqueous solution and a paste is water, it means that a large portion of the cost of their storage and transportation is for water. Because of their high water content, furthermore, high concentration aqueous solutions and pastes of such an agent tend to become degraded while in stage or being transported, and floating substances and sediments are frequently generated in low concentration aqueous solutions prepared therefrom. Even if such a low concentration aqueous solution is applied to synthetic fibers, it is not always possible to provide the synthetic fibers with desired characteristics.